Astronauts check shuttle's thermal skin

Published 7:00 pm, Thursday, March 20, 2008

Endeavour's astronauts inspected their ship's thermal skin Friday for any possible damage from orbital debris, using a laser-tipped boom that will be left behind at the international space station.

The slow and meticulous survey normally is conducted after a space shuttle leaves the space station. This time, it was done with the shuttle still docked. That's because the 50-foot inspection boom will be left behind for the next shuttle crew.

There won't be room in Discovery's payload bay for an inspection boom in May; Japan's enormous Kibo lab will take up almost every square inch. Two astronauts will attach the boom to the outside of the space station Saturday night during the fifth and final spacewalk of the shuttle mission.

Shortly after reaching orbit last week, the astronauts hooked up the boom to Endeavour's 50-foot robot arm to check the wings and nose for any launch damage. None was found. They repeated the inspection Friday in the remote chance the wings or nose took a micrometeorite or space junk hit during the past 1 1/2 weeks.

NASA was still glowing over the success of Thursday night's thermal tile repair test. Two spacewalking astronauts used a high-tech caulk gun to squirt goo into the holes of deliberately damaged shuttle tile samples. The material reacted much like engineers expected: Bubbles formed in the putty and caused it to expand, but not too much.

Once back on Earth, the tile samples will be subjected to more than 2,000 degrees to mimic the heat of re-entry, then dissected and analyzed.

It was the last safety-related space demonstration stemming from the 2003 Columbia disaster.

Engineers, meanwhile, were trying to figure how to deal with a problem with Dextre, the space station's new robot. The shoulder joint in one of the robot's 11-foot arms was not responding properly, after being moved in preparation for Thursday night's spacewalk. The joint did not know what position it was in.

Flight director Ginger Kerrick said the Canadian Space Agency _ which supplied the $200 million-plus robot _ cannot perform a diagnostic test until the "unknown position" computer message for the shoulder joint is cleared. Engineers are considering a software patch, she said.

The problem does not affect the rest of Endeavour's space station visit, Kerrick said.

Endeavour's astronauts put Dextre together during the first half of their 16-day mission and also attached the first piece of Japan's Kibo lab, a storage compartment.

Saturday night's spacewalk will wrap up their space station work and clear the way for an undocking on Monday night. It will be the most spacewalks ever performed during a joint shuttle-station flight.